Electric circuit breaker



Oct. 23, .1934. K. BAUERSCHMIDT 1,978,246

I ELECTRIC CIRCUIT BREAKER Filed Jan. 26, 1934 lsl, n

Inventor:

Kuno Bauer-Schmidt.

' 2.8M by ilmtbornggf Patented Oct. 23, 1934 UNITED STATES PATENT OFFICE ELECTRIC (HRCUI'J? BREAKER Application January 26, 1934, Serial No. 708,447

In Germany March 31, 1933 7 Claims.

My invention relates to electric circuit breakers,

more particularly to liquid-break or oil circuit.

breakers of the well known finger-contact type whereina movable contact member or bridging conductor is engaged or clasped at opposite sides thereof by coacting finger contact members, and

has for its principal object the provision of improved circuit breaker contact structure of the aforesaid type.

following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Referring more particularly to the drawing, Fig. 1 is an elevational end view, taken along the line 1-1 of Fig. 2, of circuit breaker contact structure embodying the present invention and Fig. 2 is a side view of the aforesaid contact structure.

Fig. 1 illustrates relatively movable contact structure of one pole of a liquid-break circuit breaker comprising a so-called fixed contact structure 1 and a movable contact member 2, the contact structure being in open circuit position. The fixed contact structure includes a plurality of pairs of coacting contact members 3 and 4, known generally 'as finger contacts, arranged to engage the opposite sides of the'movable contact or blade 2 when the same is elevated to the closed circuit position. The aforesaid contact structure is immersed in a suitable insulating liquid as oil.

lhe contact members 3 and 4 each comprise a conducting strip rectangular in cross section and pivotally supported at 5 and 6, respectively, so that there is a certain degree of lost motion or play between a contact member and its pivot pin as clearly illustrated by Fig. 1. The ends of the contact members 3 and 4 adjacent theloose pivotal mountings thereof are shaped as at 3' and 4', respectively, to have a combined rolling and sliding contact engagement with coacting contact surfaces formed by a conducting member 7 which is in turn connected to the lead-in conductor stud 8. Such direct contact engagement is made possible by the play at the pivots 5 and 6.

Referring more particularly to 2, the conducting member '1 comprises a contact supporting block at the opposite ends of which depend plates 9 and 10 in which the pivot pins for the contact members are mounted. As illustrated in Figs. 1 and 2, a plurality of contact members 3 and 4 are spaced with respect to each other as My invention will be more fully set forth in the by spacing washers 6' and mounted on the respective transversely extending pivot pins so that the movable bridging member 2 is engaged at each side thereof by a plurality of contacts.

For the purpose of biasing the finger contact 0 members towards each other and into contact engagement with the bridging member in the closed circuit position, resilient means as springs 11 and 12 are positioned under initial tension between the finger contacts 3 and 4 and the re- 6 spective ends 11' and 12' of arod member 13 which extends adjacent and between the finger contacts as illustrated by Fig. 2. Each rod 13 is provided with bearing plates 13' slidably -mounted thereon and arranged to engage two 7 pairs of coacting contact fingers. A bar 14 is supported between the lower ends of the plates 9 and 10 and forms a positioning and stop member for the finger contacts as illustrated by Fig. 1.

When the movable contact blade 2 is elevated to close the circuit the finger contacts 3 and 4 are engaged and wedged apart by the movable contact, the tensioned springs 11, 12 serving to establish uniform contact engagement between the coacting surfaces of the contacts. The springs 11 and 12 therefore not only serve to equalize the contact pressure at opposite sides of the movable contact and to compensate for a limited degree of mis-alinement between the center lines of the fixed and movable contact structures but also to press the ends 3' and 4' of the finger contacts directly into engagement with the conducting member 7. By reason of this direct contact engagement between the finger contacts and the stationary conductor stud the current may be carried through the stationary contact structure without the provision of the usual flexible conductors interconnecting these elementsand without relying on the pivotal support which is considered an unsatisfactory electrical connection. Furthermore, the combined rolling and wiping action of the contact portions 3" and 4 at the coacting contact surfaces serves to maintain good electrical contact. It will be apparent that the desired contactpressure may readily be obtained by adjusting the tension of the springs 11 and 12 and also by varying the distance of the application of spring pressure from the pivot points.

I In addition to compensating for a limited degree of horizontal mis-alinement of the contacts, the contact arrangement likewise provides for a limited degree of angular mis-alinement of the bridging member. In the event of such misalinement the coacting'pairs of finger contacts engage with equal contact pressure the opposite sides of the bridging member even though the finger contacts of adjacent pairs are out of alinement. In other words the finger contacts of each group make equalized contact engagement with the corresponding portion of the bridging member regardless of the position of the other contact fingers.

It will be apparent that the biasing means including the rod 13 which is common to oppositely disposed finger contacts may be related, if desired, to a single pair of finger contacts or to a plurality of pairs, depending on the current-carrying and other requirements of the circuit breakers. a a

It should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from th spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In an electric circuit breaker, relatively movable contact structure comprising a pair of contact members, means providing a loose pivotal mounting for each of said members, a movable contact arranged to be engaged at opposite sides thereof by said contact members in the closed members and provided with contact surfaces independent of said pivotal mounting arranged to be engaged by the corresponding contact members, a movable contact positioned between said contact members in the closed circuit position, and means resiliently biasing said contact members into engagement with said movable contact, said resilient means likewise biasing said contact members in the closed "circuit position into combined rolling and wiping contact engagement with said stationary conducting member.

3. In an electric circuit breaker, relatively movable contact structure comprising a pair of contact members, means including a pair of pins providing a loose pivotal mounting for each of said members, a conducting member to which said pins are secured, said conducting member and said contact members having coacting contact surfaces independent of said pins included in the circuit, a movable contact positioned between said contact members in the closed circuit position, and means resiliently biasing said coacting contact surfaces into direct engagement in said closed circuit position by reason of the aforesaid loose pivotal mounting.

4, In an electric circuit breaker, relatively movable contact structure comprising a pair of contact members, contact supporting structure therefor including pivotal mountings for said contact members, a pair of plate members depending from said supporting structure at opposite sides of said contact members, a positioning member supported between the lower ends of said plate members and between said contactmembers, and a movable contact positioned between said contact members in the closed circuit position.

5. In an electric circuit breaker, relatively movable contact structure comprising a stationary conducting member, a pair of contact members, means depending from opposite sides of said conducting member forming pivotal supports for said contact members, said contact members being in direct contact engagement with said conducting member in the closed circuit position, and a movable contact positioned between said contact members in said closed circuit position.

6. In an electric circuit breaker, relatively movable contact structure comprising a stationary conducting member, a plurality of pairs of oppositelydisposed contact members pivotally mounted with respect to said conducting member, said contact members arranged to be in direct contact engagement with said conducting member in the closed circuit position independently of the pivotal mountings thereof, a movable conducting blade positioned between said contact members in the closed circuit position so that each side of said blade is engaged by a plurality of contact members, and means including a pair of springs and a member common to a pair of coacting contact members for biasing said contact members individually into equalized contact engagement with said blades and into direct contact engagement with said conducting members.

. 7. In an electric circuit breaker, relatively movable contact structure comprising a pair of finger contact members, a relatively fixed conducting member, means loosely mounting said contact members for pivotal movement with respect to said conducting member, a movable contact positioned between said finger contact members in the closed circuit position, said finger contact members and said conducting member having coacting contactsurfaces independent of said pivotal mounting arranged for combined rolling and wiping engagement, and resilient means for biasing said finger contact members into engagement with said movable contact and said conducting member. 7

KUNO BAUERSCHMIDT.

, I DISCLAIMER 1,978,246 .Kun0 Bauerschmidt, Berlin-Karlshorst, Germany. ELECTRIC CIRCUIT BREAKER. Patent dated October 23, 1934. Disclaimer filed July 27,

1935, by the assignee, General Electric Company.

Hereby enters this disclaimer to that part of the claim in the specification of said Letters Patent which is in the following Words, to wit:

1. In an electric circuit breakenrelatively movable contact structure comprising a pair of contact members, means providing a loose pivotal mounting for each of said members, a movable contact arranged to be engaged at opposite sides thereof by said contact members in the closed-circuit position, and means resiliently biasing said members into contact engagement with said movable contacts, said contact members likewise biased into contact engagement in the closed circuit position with stationary conducting means independently of said pivotal. mounting.

2. In an electric circuit breaker, relativelyv movable contactstructure comprising a pair of contact members, means providing a loose pivotal mounting for each of said members, a stationary conducting imernber disposed between said contact members and provided with contact surfaces independent of said pivotal mounting arranged to be engaged by the corresponding contact members, a movable contact positioned between said contact members in the closed circuit position, and means resiliently biasing'said contact members into engagement with said movable. contact, said resilient means likewise biasing said contact members in the closed circuit position, into cbombined rolling and wiping contact engagement with said stationary conducting A mem er. 1

3. In an electric circuit breaker, relatively movable contactstructure comprising a pair of contact members, means including a pair of pins providing a loose pivotal mounting for each of said members, a conducting member to "which said pins are carried, said conducting member and said contact members having coacting contact surfaces independent of said pins included in the circuit, a movable contact positioned between said contact members in the closed circuitposition, and means resiliently biasing said coacting contact surfaces into direct engagement in said closed circuit position by reason of the aforesaid loose pivotal mounting.

5. In an electric circuitbreaker, relatively movable contactstructure comprising a'stationary' conducting member, a pair of contact members, means depending from opposite sides of said conducting member forming pivotal supports for said contact members, said contact members being in direct contact-engagement with said conducting member in the closed circuit position, and a movable" contact positioned between saidcontact members in said closed circuit positi0n..

" In an electriccircuit breaker, relatively movable contact structure comprising a stationary conducting member, a plurality of pairsfof oppositely disposed contact z-members pivotally"inounted withJrespect to said conducting member, said contact 1 'inembers arranged to' e. in direct contact engagement with said conducting member in the closed circuit position independently of the pivotal mountings thereof, a movable conducting blade positioned between said contact members in the closedcircuit positionso that each side of said blade is engaged by a plurality of contact members, and vmeans including'a pair of springs and a member common to a pair of coacting contactrmembers for biasing said contact members individually into equalized contact engagement with said blades andinto direct contact engagement with said conducting mem ers;

7, In an electric circuit breaker, relatively movable contact structurecomprising a pair of finger-contact members, a relatively -fixed conductingmember, means loosely mounting said-contact members for pivotal movement with respect to said conducting member, amovable contact positioned between said finger contact members in the closed circuit position, .saidfinger contact members and said conducting member having co'acting contactsurfaces independent of said pivotal mounting arranged for combined rollingand wiping engagement, and resilient means for biasing said fingerv 'contafizt members into engagement with said'ymovable contact and said conducting mem er. t. v

[Ofiicial Gazette Aug'ust Q0, 1935.] 

